The JCS Memorandum released today is real, and is a message to the Joint Force to remind members of the legal facts, as they stand today. Agree or disagree with what is going on, President Trump is still the Commander in Chief, the Presidential Inauguration is still scheduled for 20 January 2021, and the current President-elect is Joe Biden, and Service Members have taken oaths to support and defend the Constitution.
And anyone who thinks war has a future expiration date and timestamp on it, hasn't paid any attention to the world over the last decades.
Hold the line Brothers!
Do not let them get you down by twisting the JCS message, POTUS's statement at the wall, etc. into something it is not!